- Classification study: Bone marrow or peripheral blood samples are collected and may be analyzed for B- and T-lineage antigen screening; cytochemical stains; cytogenetics (karyotype); immunophenotype screening for MLL, E2A-PBX1, TEL-AML1; immunophenotype detection of minimal-residual disease (MRD); FCM ploidy (DNA index); trisomies 4 and 10 (FISH); molecular testing for BCR/ABL, MLL rearrangements, E2A-PBX1, and TEL-AML1; molecular detection of MRD - Tγ, Tδ, or IgH; acute lymphoblastic leukemia (ALL) cell bank; special T-ALL reference laboratory studies (role of tumor suppressor genes in T-ALL and drug sensitivity profiles in T-ALL); special study for mature B-ALL [t(18;14)(a24;q32)] by FISH; and hematopathology consultation concerning morphology and cytochemistry. The immunophenotype results are used to assign patients to a treatment protocol, to assign patients to post-induction (day 28) risk group and treatment for patients with B-precursor (non-T, non-B) ALL, and to use as reference laboratory MRD results.